GitHub hit by DDoS attack second day in a row

GitHub hit by DDoS attack second day in a row

GitHub is having one hell of a week, with four outages in five weekdays. The social coding site is currently being hit by a Distributed Denial of Service (DDoS) attack, the second one in two days. The site’s engineers are working on fixing the issue, which thankfully has not brought the whole site to its knees (unlike yesterday), but has only resulted in a “partial service outage.”

Here’s what we know so far (we’ll update this list as we learn more courtesy of

12:15 PM PST: We are investigating issues with pages serving.
12:41 PM PST: Pages is currently being hit with a DoS attack. We’re working to mitigate the attack.
01:22 PM PST: We’re still working to mitigate the attack on Pages.
02:11 PM PST: GitHub Pages service has returned to normal. All systems go!
02:16 PM PST: A small percentage of git repos will be unvailable while we recover a fileserver pair. Updates as we have them.
02:25 PM PST: All git repositories are now accessible.

On Tuesday, GitHub experienced a 26-minute partial service outage (a network issue at one of its upstream providers), and on Wednesday the service experienced a 24-minute partial service outage (errors with its search service). On Thursday (yesterday), the site experienced a major service outage that lasted 99 minutes and that GitHub attributed to a DDoS attack. On Friday (today), we’re back to a partial service outage, but this one is again due to a DDoS attack.

For reference, here’s what happened yesterday:

01:05 PM PST: We are investigating issues with
01:17 PM PST: We’re experiencing some connectivity issues at the moment. is currently unavailable while we resolve this.
01:33 PM PST: We are experiencing issues due to a DDOS attack, working hard to restore service
01:41 PM PST: Performance is still substantially sub par as we fend of the connection flood. We’re on it.
01:41 PM PST: We’ve temporarily disabled service on port 80 while we investigate the source of a connection flood. HTTPS, GIT, and SSH service are unaffected.
02:44 PM PST: Performance is stabilizing. We’re investigating additional mitigation strategies to harden ourselves against future attacks, similar or otherwise.

We’ll keep you posted to see if this devolves to a major service outage or if GitHub manages to fix the problem. As you can see in the log above, GitHub yesterday started looking into mitigation strategies to fight DDoS attacks, though it’s not yet clear if the company has implemented these yet.

We have contacted GitHub for more information. We will update this article if and when we hear back.

Update at 5:25PM EST: GitHub is back for all users. Today’s outage lasted a total of 130 minutes, the longest yet this week.

Image credit: Adam Fast

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